Esters with antimicrobial, bioresistant and fungal resistant properties

ABSTRACT

A bromine/nitro moiety linked into the backbone of an ester or other compound over a wide range of occurrence rates provides antimicrobial, bio-resistant and fungal resistant properties for metal working fluids (MWF)s and other coatings. The moiety can be have the bromo and nitro groups linked to the same or different carbon atoms. The present invention also relates to urethanes, urea, amides, imides, carbonates, ethers, siloxanes, and many other types of linkages essential to MWF bases.

This is a continuation of application Ser. No. 14/558,122 filed Dec. 2,2014, now U.S. Pat. No. 9,290,437 issued Mar. 22, 2016 which was acontinuation of application Ser. No. 14/293,054 filed Jun. 2, 2014, nowU.S. Pat. No. 8,901,332 issued Dec. 2, 2014 which was a divisional ofapplication Ser. No. 13/741,518 filed Jan. 15, 2013, now U.S. Pat. No.8,742,151 issued Jun. 3, 2014. Application Ser. No. 13/741,518 was acontinuation of application Ser. No. 13/351,512 filed Jan. 17, 2012, nowabandoned, which was a continuation of application Ser. No. 12/965,252filed Dec. 10, 2010, now abandoned, which was a divisional ofapplication Ser. No. 12/287,726 filed Oct. 10, 2008, now abandoned,which was a continuation-in-part of application Ser. No. 11/800,569filed May 7, 2007, now U.S. Pat. No. 7,439,376 issued Oct. 21, 2008,which was a continuation in part of application Ser. No. 10/603,356filed Jun. 25, 2003, now abandoned, which claimed priority from U.S.Provisional patent application No. 60/392,007 filed Jun. 26, 2002.Application Ser. Nos. 14/558,122, 14,293,054, 13/741,518, 13/351,512,12/965,252, 12/287,726, 11/800,569, 10/603,356 and 60/392,007 are herebyincorporated by reference in their entireties. This application alsoincorporates by reference my patent application Ser. No. 10/350,928filed Jan. 23, 2003 entitled Polymers with Antimicrobial, Bioresistantand Fungal Resistant Properties in its entirety.

The text of this application is substantially identical to that ofgrandparent application Ser. No. 10/603,356.

BACKGROUND

1. Field of the Invention

The present invention relates to the field of esters and moreparticularly to esters with bioresistant, fungal resistant andantimicrobial/antifungal properties.

2. Description of The Problem Solved by the Invention

Due to environmental regulation, the use of tin, mercury, lead, andother heavy metals to control the growth of microbes in organic systemsis now prohibited. In particular metal working fluids (MWF)and metalworking fluid bases suffer a failure mode when attacked by microbes. Theproblem is especially acute in water extendable and emulsion MWFsystems. The attack of the microbes on the MWF base causes the pH of thesystem to drop, which destabilizes the emulsion and also increases thecorrosion of metal parts that are exposed to the attacked fluid. Asidefrom the obvious problems that microbes cause in MWFs, operator healthissues also arise due to continuous exposure to high levels of bacteria.

Current systems in place include the addition of biocides to the fluidto prevent the bacteria from breaking down the MWF. One common biocidein use is the family of isothiazolinones. This product family isgenerally hazardous to handle and causes sensitization in many peoplewhen exposed repeatedly. The sensitization often takes the form ofitching all over the body, or hives when any part is in contact with theisothiazolinone. Additionally, the isothiazolinone family is relativelyunstable at the alkaline pH that most MWFs are maintained at. This thenrequires the operator to add more material on a regular basis. Also, themicrobes develop a tolerance to isothiazolinones. This again requiresthe operator to increase the amount of the isothiazolinone in thesystem.

A second biocide technology is the use of formaldehyde condensates.These materials are generally hazardous, but do not lead tosensitization of the operators in contact with the MWF. The formaldehydecondensates do contribute to free formaldehyde in the workplace, but theresults are not consistent as to how much formaldehyde they contributeto the workplace atmosphere. Most formaldehyde condensates are volatileand evaporate. This requires their replenishment on a regular basis evenwhen they are not consumed.

What is needed is a system that uses an ester as the MWF base that isnot susceptible to microbial attack. The material fails to act as a foodsource for the microbes that are able to digest the current MWF bases.

SUMMARY OF THE INVENTION

The present invention relates to an ester that contains an antimicrobialmoiety that is linked into the backbone of the molecule. This moiety is,in general, a bromine atom and a nitro (NO2) group linked to one or moreof the carbon atoms forming the backbone of the molecule that is the MWFbase. While the present invention is directed primarily to esters, themoiety taught should also be effective when linked onto a carbon atom inthe backbone of any suitable MWF base molecule. The moiety can appear inthe backbone of the MWF base in various levels of occurrence. Apreferred occurrence of around 1000 parts per million on a weight basisis effective; however the frequency of occurrence can be as low as 5parts per million to as high as 99-100%. MWF base types within the scopeof the invention include, but are not limited to urethane, urea, amide,ester, carbonate, ether, and siloxane linkages.

It is well known in the art to combine a carboxylic acid and an alcoholin the presence of a suitable catalyst to form an ester. The presentinvention adds a bromo-nitro substituted alcohol, diol or polyol to astandard alcohol to be used in the ester synthesis. The proportion ofsubstituted compound used is chosen to yield the desired concentrationof the moiety in the final MWF base. A preferred diol for theapplication is bromonitropropanediol or 2-bromo-2-nitro-propane-1-3-diolor simply BNPD. This particular diol is a solid material with varyingdegrees of solubility in other alcohols and has proven antimicrobialproperties.

In addition, BNPD has been shown to have no tetragenecy (cancer causingeffects) and is approved by the CFTA at levels of up to 0.1% for use incosmetics. BNPD has also been used in baby wipes for its antimicrobialproperties.

The fact that the active antimicrobial moiety is covalently linkeddirectly into the backbone of the ester reduces its breakdown at thealkaline pHs required of MWFs. In addition, the moiety is notphoto-active or decomposed by sunlight or exposure to mineral salts suchas calcium chloride, magnesium hydroxide and sodium chloride as arefound in hard and softened water.

Because BNPD is a substituted diol, it is a natural reactant to formpart of an ester linkage with a carboxylic acid. Also, being a diol, itmixes directly with a wide range of alcohols or polyols and otherperformance enhancing additives with no difficulty or adverse reactions.In fact, it can be mixed in any desired proportion (to the extent thatit is soluble) with any standard alcohol used in synthesizing esters,ethers, or urethane type linkages.

While bromonitropropanediol (BNPD) is the preferred antimicrobial agentbecause of its proven activity and its benign effects on the environmentand on humans, other alcohols, diols or polyols with bromine and nitrogroups linked at the same or different carbon atoms can also beincorporated into the backbone of MWF bases. Any other antimicrobialagents that can be linked onto an alcohol reacted linkage are within thescope of the present invention.

DESCRIPTION OF THE FIGURES

FIG. 1 shows the formation of an ester linkage with BNPD.

FIG. 2 shows treatment of BNPD with ammonium hydroxide to form an amide.

FIG. 3 shows the formation of both urethane and urea linkages.

FIG. 4 shows the synthesis of an acid functional, pendant fatty chain.

DETAILED DESCRIPTION OF THE INVENTION

It is well known in the art to combine alcohols with carboxylic acids toform ester linkages. One example is isopropyl oleate, the ester ofisopropyl alcohol and oleic acid. Polyols are also commonly used, suchas in the production of Lexolube 21-214 by Innolex. A typical ester willhave the following formula:

where R typically comes from the original carboxylic acid and R′typically comes from the original alcohol. It is well known in the artthat R and R′ can be the same or different. The typical example notedabove as isopropyl oleate has the following structure:

The compound bromonitropropanediol or 2-bromo-2-nitro-propane-1,3-diol(BNPD) has known antimicrobial properties. Tests on this compound haveshown that it is effective against various strains of both gram positiveand gram negative bacteria in concentrations of 1-50 ppm with theaverage minimum inhibitory concentration being around 25 ppm. Inaddition, work has indicated that BNPD is also antifungal. BNPD has thefollowing structure:

Because BNPD is a polyol, it can be combined with other alcohols, diols,or polyols in the manufacture of the esters used as MWF bases. Inparticular, BNPD alone or mixed with other alcohols, can be combinedwith carboxylic acids to form esters that are suitable for use as MWFbases. This causes the active moiety to become covalently linked intothe ester. In the case of the oleate ester, the product is:

Or more generally:

The dioleate ester can easily be made, which has the followingstructure:

Or more generally, for the diester:

While BNPD is a preferred polyol starting point to link the activemoiety into an ester MWF base, it is within the scope of the presentinvention to use many other materials that contain a bromine atom andnitro group linked near one another. The preferred class of compoundscontains the bromine and nitro linked to the same carbon atom; however,it is felt that a moiety where the bromine and nitro are not linked tothe same carbon, but near each other will still be effective. Many othersimilar compounds can also be used. In particular,bromonitromethanediol, bromonitroethanediol, bromo-nitrobutanediol, etc.can also be substituted into molecule backbones with similar results. Itshould be understood that these are just examples of the many compoundswithin the scope of the present invention. The prior art has shown thatbromonitromethane is effective for the treatment of nematodes in thesoil (See U.S. Pat. No. 5,013,762 which is hereby incorporated byreference) and as a general biocide (See U.S. Pat. No. 5,866,511 whichis hereby incorporated by reference). It is felt thatbromonitromethanediol and similar diols are equally effective.

The present invention also includes using a BNPD or BNPD analog as theterminus, such as:

Where R′ can be, but is not limited, to CH2OH, OH, CH3, or H.

The present invention reacts BNPD or similar substituted alcohols, diolsor polyols, with or without the aid of a solvent or co-solvent, with acarboxylic acid to form the ester MWF base.

The present invention results in a covalently linked bromine/nitromoiety in the backbone of an ester at some frequency of occurrence thatprovides antibacterial or anti-fungal effects. The present inventionrelates to ester, urethane, urea, amides, imides, carbonates, ethers,siloxanes, and many other types of linkages essential to MWF bases.

FIG. 1 shows the formation of an ester linkage with BNPD. FIG. 2 showstreatment of BNPD with ammonium hydroxide to form a bromonitro amine ordiamine which can then be combined with an aldehyde or carboxylic acidto form an amide. FIG. 3 shows the formation of both urethane and urealinkages. FIG. 4 shows the synthesis of an acid functional, pendantfatty chain.

The examples and illustrations presented herein are for the purpose ofunderstanding the concepts of the present invention. It will be clear toone with ordinary skill in the art that many other examples andstructures are within the scope of the present invention. This appliesparticularly to classes of linkages where an example of one particularstructure has been given; it will be appreciated by one skilled in theart that in such a case, the entire class of compound is within thescope of the present invention.

EXAMPLE 1 Production of a Metal Working Fluid Base

A vessel equipped with a nitrogen blanket and condenser was charged with1128 g (4 moles) of oleic acid, 400 g BNPD (2 moles) and 2 g conc.Sulfuric acid. The vessel was heated to 288 F when condensation began.The temperature leveled off between 352 F and 356 F and was kept attemperature for 3 hours. The BNPD dioleate recovered was a dark brownishliquid.

The dioleate produced was then incorporated into a standard MWF base at10% (1,300 PPM BNPD) in the concentrate by substituting it for part ofthe existing ester. The bases were then subjected to ASTM 3946-92,“Standard Test Method for Evaluating the Bacteria Resistance ofWater-Dilutable Metal Working Fluids”. On Day 5 of the testing, the BNPDester containing fluid showed bacterial count of 3×10̂3 CFU/ml, which isconsidered under control. The control sample had a bacterial count of1×10̂7, which is not considered under control.

At an incorporation level of 6% (823 PPM BNPD) in the standard MWF basea bacterial count of 1.5×10̂4 CFU/ml was observed after five days oftesting. This level is still considered under control and a significantimprovement over the 1×10̂7 CFU/ml observed in the standard MWF basewithout any BNPD substituted ester.

A slight decrease in wear was also noted with the BNPD substitutedproducts in the pin and v-block tests performed.

EXAMPLE 2 Synthesis of Acid Functional, Pendant Fatty Chain Containing,BNPD Ester

In a vessel with heat, agitation, condenser, and nitrogen blanketing ischarged 400 g (2 moles) of BNPD, 616 g (4 moles) of1,2-Cyclohexanedicarboxylic anhydride (HHPA) and 150 g xylene as areflux solvent. The vessel is heated to 323 F at which point thereaction exothermed and began to darken. The temperature was thenreduced and held at 302 F for one hour. 1162 g of final product wasrecovered that was a thick, dark transparent liquid. This product willbe referred to as HHPA/BNPD-003.

In a vessel with heat, agitation, condenser, and nitrogen blanketing ischarged 706 g of HHPA/BNPD-003 from above, 806 g of Crisamine PCD-2, 2mole ethoxylate of primary coco amine, and 150 g xylene as a refluxsolvent. The vessel is heated to 350 F for three hours until thetheoretical water loss was collected in the trap and the evolution ofwater stopped. Approximately 1,400 g of a dark, thick translucent liquidwas recovered. This product will be referred to as HHPA/BNPD/coco diol.

In a vessel with heat, agitation, condenser, and nitrogen blanketing ischarged 526 g of HHPA/BNPD/-003 diol from above, 146 g of adipic acid,and 150 g xylene as a reflux solvent. The vessel is heated to 400 F for2.5 hours until the theoretical water loss was collected in the trap andthe evolution of water stopped. Approximately 600 g of a dark, thicktranslucent liquid was recovered. The synthesis and structure is shownin FIG. 4.

I claim:
 1. A molecule of the following structure:

where R and R′ are equal or not equal and are saturated or unsaturated,linear or branched alkyl from 5-22 carbons, polysiloxane orpolydimethylsiloxane with molecular weights up to 2000, where A isselected from the group consisting of linear or branched, saturated orunsaturated, alkyl, alkynal with from 1-22 carbons, or —Br.
 2. Themolecule of claim 1 where R═R′═—(CH₂)₇CH₃ and A═—Br.
 3. A metal workingfluid base comprising a molecule according to claim
 1. 4. A surfactantcomprising a molecule according to claim
 1. 5. A foaming or anti-foamingagent comprising a molecule according to claim 1.